Modeling glacial-interglacial changes in global fire regimes and trace gas emissions

Climate at the Last Glacial Maximum (LGM) together with low atmospheric CO₂ concentration forced a shift in vegetation zones, generally favored grasses over woody plants and allowed the colonization of continental shelves. Many studies using models and/or palaeo data have focused on reconstructing climate and vegetation changes between LGM and present, but the implications for changes in fire regime and atmospheric chemistry have not previously been analyzed. We have investigated possible global changes in fire regime using climate model simulations of the LGM to drive the Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ) with its embedded fire model, Glob-FIRM. Simulation results reveal a pronounced shift of pyrogenic emission sources to lower latitudes. Global total emissions were slightly reduced. Enhanced nitrogen oxides emissions in the tropics could potentially have increased the oxidizing capacity of the atmosphere, helping to explain the low atmospheric methane concentrations during glacial periods as observed in the ice core records.